Paris — Few top fugitives, including Osama bin Laden, have been on the verge of apprehension longer than Serbian Gen. Ratko Mladic, the brutal, operational face of genocide in the Balkans in the 1990s.

For years, international prosecutors and leaders have left Belgrade with assurances that Mr. Mladic is about to be captured. Now, 15 years after his indictment for war crimes, a Serbian judge ruled that Mladic was medically fit to be extradited to face trial at the Hague, despite his lawyer’s objections and likely appeal.

Together the three men helped ignite orgies of ethnic hate and killing in the Balkans. Coming immediately after the heady fall of the Berlin Wall and end of the Soviet sphere of influence in 1989, sometimes called “the end of history,” Mladic played a direct role in opening a darker side of human history.

For a Europe that swore “never again” after the gas chambers of Auschwitz and the official demonization of Jews, the chaos and ethnic cleansing Mladic helped unleash in the Balkans was an enormous test for Western values and resolve.

That test often proved too much, analysts say. In his “heyday,” Mladic, who was born in Bosnia in 1943, confounded US and European diplomats and leaders for years with endless negotiations and deals that were rarely kept. His military acts, as recorded in trials at the Hague, include directing the siege of Sarajevo, ethnic cleansing, the organized terror of civilians, and the killing of at least 8,000 Bosnian Muslim men and boys at Srebrenica, a word now synonymous with massacre.

“Mladic was handpicked for the role. He distinguished himself in ethnic cleansing in Croatia, he was a guy who was ready to fight,” says Marko Attila Hoare, an expert on Bosnia at Kingston University in Britain. “Mladic was groomed … and created by the Milosevic regime and gained more autonomy as the war went on and eventually led to Srebrenica. Mladic was the architect of Srebrenica.”

While Mr. Karadizic, who was arrested two years ago while hiding in Belgrade (he was disguised with a flowing beard as a new age healer), was the flamboyant face and articulator of Serb nationalism, Mladic was the doer.

He is regarded as the enabler, the person who gave orders to troops who enormously admired him, the military leader who supposedly would never be taken alive. According to news reports, Mladic did have two guns in his possession when he was apprehended in a small town in northern Serbia, but was cooperative.

For years, Serbia’s effort to join the European Union have been blocked by its inability or unwillingness to capture Mladic, whose sway among hard-core patriots in the vast Serbian security establishment had been legendary. As Dejan Anastasijevic, a long-time Mladic-watcher and leading Serb journalist put it, the inability to arrest Mladic may well have boiled down to one word: “fear.”

Mladic was a young officer who rose to prominence in the murky and chaotic days of the early 1990s, when the former Yugoslavia and its army began to break up and to be essentially reorganized as a Serbian army fitted to carry out a “Greater Serbia” policy. The old Army made up of officers and troops from all parts of Yugoslavia – from Macedonia to Slovenia and Croatia – began to dissolve as these former regions declared independence.

But Belgrade under Mr. Milosevic continued with a “Yugoslav” army that retained a core Serbian element that would attempt to join together large swaths of territory where Serbs were declared a majority.

At the heart of the conflict in the early days of war was Bosnia, the Balkan heartland, where Muslims, Croats, and Serbs lived in roughly equal numbers in the capital Sarajevo. When it became clear that Muslims and Croats in Sarajevo and Bosnia did not want to live in a rump Yugoslavia controlled by a toxic Serbian ethnic nationalist ideology that regarded them as lesser humans deserving of lesser rights, Bosnia declared independence.

Mladic found his military niche in this breakup. Together with Mr. Karadzic, he took command of Serb forces and began a siege of cosmopolitan Sarajevo. The city had a long history of art and music and religious tolerance, with Eastern Orthodox, Muslim, Protestant, Roman Catholic, Jewish, and other houses of worship built nearly side by side in the old town.

In many ways, it was the idea of the city and its modern, liberal and interethnic traditions, including intermarriage, that were most hated by the often rural-born Serb troops. Mladic’s forces positioned themselves on the hills above the city, sniping at citizens, lobbing mortars, and undertaking a policy of bombardment that, Mladic famously said, was designed to make the inhabitants of Sarajevo “go insane.”

The siege lasted nearly three years, as United Nations observers daily counted the number of mortars hitting downtown, a figure that regularly ran into the hundreds – even as the Bosnian government pleaded with the Western powers to act.

Action was finally forthcoming after the massacre of Srebrenica, a so-called UN “safe haven” for Bosnian Muslims. Serb forces controlled by Mladic finally overran that tiny enclave protected by Dutch UN blue helmets. The Bosnian men exited the area and attempted to escape – but were tracked and slaughtered en route, and buried, and then reburied, in various mass graves.